Azimuth compass



B. M. GREEN AZIMUTH COMPASS Jan. 14, 1936.

Filed Jan. 2Q, 1934 3 Sheets-Sheet 1 Burton 61 22 Jan. 14, 1936. B. M.GREEN 2,028,063

AZ IMUTH COMPAS S Filed Jan. 20, 1934 5 Sheets-Sheet 2 Barlow #wen/ mwwgJan. 14, 1936. a. M. GREEN 2,028,063

AZIMUTH COMPASS Filed Jan. 20, 1934 ,3 Sheets-Sheet 3 flll'i'alt M greatPatented Jan. 14, 1936 PATENT OFFICE AZIMUTH COMPASS Burton M. Green,Brooklyn, N. Y. Application January 20, 1934, Serial No. 707,585

12 Claims.

My invention relates to azimuth compasses, and particularly to anazimuth ring or circle to be associated with a mariners or navigators orsurveyors or other compass, and to be used in showing the direction withrespect to the compass of the sun or a star or a landmark or othercelestial or terrestrial indication, point, object or the like.

An object of this invention is to provide a .device of this characterthat can be employed in place of structures now used, and which does notrequire projection of a light ray, but rather only a discerniblereflection of an image, thus being adaptable for use in focusing uponand refleeting images of terrestrial points, and upon 0 stars and othercelestial points, as well as the sun.

A further object is to provide a structure of this character that can befocused upon nonluminousobjects, upon lighted objects, and'upon the sun,stars or other luminous or bright bodies when in full briiliancy andwhen partially dulled or obscured by clouds, mist, fog, or other causes,as no reflected transmission of light rays is necessary.

Another object is to so construct and associate the parts that theinstrument can be adjusted to focus upon and reflect an object,landmark, or

other terrestrial point substantially upon the level of the horizon, orupon the sun, a star, or other celestial point at any elevation or anglefrom the horizon up to the meridian or zenith.

Still another purpose of this invention is to provide an instrument thatwill give a full view reading of the indicating portion of the compasscard without confusion or distortion due to perspective or the like, andthat will show clearly and sharply and closely adjacent and in the samefleld of vision the desired reflected image being focused upon.

Yet another purpose is to provide a device of this character that can betemporarily or permanently associated with compasses of variousstruction and'combinations of parts which will be hereinafter set forthin connection with the drawings and then pointed out in the claims.

In the drawings:

Figure 1 is a view in perspective illustrating an adaptation of myinvention.

Fig. 2 is a plan view.

Fig. 3 is a transverse vertical view through the structure illustratedin Fig. 2.

Fig. 4 is an enlarged side elevation to better show the prismaticsupporting and mounting structure.

Fig. 5 is an enlarged sectional view to better show the mounting and.adjustment of the pris-' matic structure.

Fig. 6 is a fragmentary illustration in elevation to show'the view astaken through the sight when the structure is in use.

Fig. 7 is a broken sectional view showing one of the bearings for theimage reflector.

In the present instance I have illustrated the invention embodied withone type of azimuth ring or circle, and as used with a magnetic compassof the navigating type, but as the description progresses it will beseen that this same prismatic principle can be embodied in an attachmentto be mounted upon and operatively associated with azimuth circles ofvarious designs, and with various types of compasses, surveyinginstruments and other instruments including a compass.

Briefly, this invention contemplates the use of two reflecting prismsemployed to bring reflected images into the. line of sight and intoproximate position in the same field of. vision. One prism, orreflector, reflects a reading of the compass carried in the plane of theline of sight, and the second prism, preferably mounted directly overthe first prism, is adjustable to bring the reflected image of acelestial or terrestrial body or object into the line of sightcoinciding with the reflecting compass field in the first prism, therebygiving two images reflected in the line of sight in a plane cutting thecenter of the compass.

The compass as here indicated, and as generally designated at l, is amagnetic marine compass of the standard type, and the gimbals 2 can bemounted in a compass box or in any other desired arrangement. Further,the gimbal arrangement can be entirely dispensed with and the structureof my invention can be applied to and used with a surveyors compass, orany other around the indicating portion of the compass l, and in thepresent instance this ring 3 is illustrated as encircling the opening ofthe compass through which the compass card 4 is visible. A flange 5 isprovided on the ring 3 to hold this ring to rotation upon a verticalaxis coinciding with the axis of rotation of the compass card 4. While Ihave shown no special means for rotating or moving this ring 3 to adjustthe same for taking bearings, any worm and rack, or other known ringrotating mechanism can be employed, and in some instances it may befound desirable to incorporate a vernier mechanism for securing a finalsharp setting of the ring.

At one side of the ring 3 a sight 6 is mounted in fixed position, andthis sight can be of any desired construction, either rigid or foldable.I have here shown a folding sight 6 having a sight slit or opening Itherethrough centered on the axis of rotation of the ring, andconsequently also the axis of rotation of the compass card, but thissight canbe of other forms and constructions, either with or without asight hair or line. As thus described, the parts can be such as haveheretofore been used in various adaptations and connections.

At a point diametrically opposite the mounting of the sight 6, amounting bracket 8 is fixed and secured upon the ring 5 by means ofscrews 9, or other suitable fastenings, and this portion 8 serves as asupporting and bearing bracket for the mechanical features of myinvention. The bracket 8 has upstanding bearing portions 10 and IIpreferably spaced substantially equally on opposite sides of a linetaken diametrically through the sight 6. These bearing portions l0 andII have bearing recesses l2 to receive and center pintle shafts l3. upona horizontal axis, and blocks 14 held in position by pins l5 are adaptedto be adjusted against the pintle shafts l3 by means of screws l6, thuspermitting adjustment and variation of the frictional bearing of thesepintle shafts. A suitable frame I1 is rigidly mounted between the innerends of pintle shafts l3 and a reflecting prism I8 is mounted in thisframe and is held secure therein by means of screws l9,- or othersuitable fastenings. This prism :liB is so mounted and disposed that oneangle is adjacent to the axis of rotation of the :pintle shafts 123, andthe prism is held with its various angular side edges in exacthorizontal relation when the ring 3 is automatically or mechanicallyleveled. The pintle shafts l3 have handwheels 20 thereon by which theprism l8 can be oscillated to focus upon a terrestrial or celestialobject or body and reflect same adjacent to the edge or angle 2| nearestthe center of oscillation.

Beneath the mounting of the image reflecting prism IS, a compassreflecting prism 22 is mounted and held in fixed position between thebrackets l0 and II. This prism 22 is disposed with its lower facesubstantially parallel with the compass card 4, and a shield or backing23 is provided on the outer face of prism 22, so that as the :prism 22is viewed through the sight 6 a portion of the compass card immediatelybeneath the prism will be reflected to be visible from the sight. Acenter line, hair, wire, or other mark is provided to establish a mark,as at 24, within the reflected field of prism 22, and this center lineis in a vertical plane cutting the sight 6 and the axis of rotation ofthe compass card 4 and the ring 3. The upper angle of prism 22 is heldto be closely adjacent to the angle edge 2| of prism I8, and the centerline mark 24 therefore serves for centering on the lower angle edge 2|of this prism i8. The prism 22 has all of its angular side edgesparallel with each other and with the side angle edges of prism l8, andconsequently all angle edges of both prisms will be disposed in truehorizontal relation when the ring 3 is leveled.

To secure proper and accurate focusing and sighting, it is necessarythat prisms I8 and 22 must be level or with their angle edges horizontaland their faces correspondingly disposed, and as a ready check to insureproper leveling, a bubble or spirit level 25 is provided immediately infront of the lower portion of prism 22, where it can be readily viewedby a person using the instrument.

As observations are to be made of and bearings are to be taken fromstars and other celestial bodies, and landmarks and other terrestrialobjects, it is desirable that a clear and fully polished prism Ill beemployed to give clearcut and sharp reflections; however, whereobservations are to be taken of the sun unobscured by clouds, it may befound that the reflected image will be too bright for satisfactory andcomfortable viewing, and in other uses it may be found desirable toshade the image reflecting prism l8. Therefore, I have provided twoshields 26 and 21 carrying dark glass or other suitable screeningmaterial, and so mounted that they can be swung to positions to clearthe prism It, as illustrated by the full lines in each instance, and canbe raised or swung up, as indicated by the dotted lines in Fig. 4. Withthe prism I8 mounted in the manner set forth, this prism can beoscillated to focus upon and reflect an image of a terrestrial objectsubstantially at or even below the horizon, and of celestial bodies atany angle above the horizon to the zenith. One or both shields 2.6 and21 can be adjusted to any desired position for the particular setting ofthe prism l8 and the angle of the sun or other body being viewed.

To take a bearing of any terrestrial point or object, or any celestialbody, it is only necessary to turn or rotate the ring to train theinstrument toward the desired bearing. The eye is then placed to thesight vane and by turning the "object or image reflecting prism IS, thedesired image will be reflected in this prism and in the held of visionthrough the sight. Then, further adjustments of the ring, and anynecessary compensating adjustments of the prism Hi can be made so thatthe image reflected therein will be focused on the center line 24 tothus be closely adjacent to and in the field of vision with thereflection of the compass card shown in base prism 22. Thus, bearings ofobjects and bodies from the horizon to the zenith can be readily andaccurately obtained, with no chance of error entering into the bearingfrom rolling or swaying of a ship or other support on which the compassis mounted.

This invention is unique in the use of two prismatic reflecting glasses,one mounted above the other, and with the lower or base prism refleetingthe arc of the compass in the line of sight when the upper or objectprism reflects the image of a terrestrial object or a celestial bodybrought into the fleld of vision by adjustment of this object compass.When adjustments are made to visibly show the proper centering of thereflected image of the body or object in the object prism, the effectiveare of the compass is reflected in the base prism, and the operator orTil aoaaooa ings are being taken. as the reflected image and thereflected reading of the compass card are in the same field of vision,and both are in a perpendicular plane cutting through the compass rioustypes; and, obviously, the structure and principle can be employed andused with substantially any azimuth, compass, or other instrument havinga revoluble ring or with which such a. ring can be employed.

While I have herein shown and described only certain specificembodiments of my invention, and have suggested only certain possiblemodifications, it will be understood and appreciated that changes andvariations can be made in the form. construction, assembly orassociation, and use without departing from the spirit and scope of myinvention.

I claim:

1. An apparatus for taking bearings comprising, a compass, a ringrevolubly associated with said compass, a sight at one side of saidring,a reflector associated with said ring at a point substantiallydiametrically opposite said sight to reflect readings of the compass,and a second reflector associated with said ring at a fixed loca tionimmediately adjacent to and within the field of vision with said firstreflector as viewed through the sight and adjustably held to permitfocusing of an image adjacent to the reflected compass reading.

2. An apparatus for taking bearingscomprising, a compass, a ringassociated with said compass and revoluble in a horizontal plane, asight at one side of said ring, a reflecting prism associated with saidring at a point opposite the sight to reflect compass readings to showvariations in the line of sight as the ring is-revolved, and areflecting prism carried by said ring immediately above and in fixedposition in the field of vision with the compass reflecting prism andadjustably mounted to allow focusing upon and reflection of an externalimage.

3. An apparatus for taking bearings comprising, a compass, a ringassociated with said compass and revoluble in a horizontal plane, asight associated with said ring at one side, a flxed refleeting prismassociated with said ring at a point diametrically opposite the sightand disposed to catch and reflect readings of the compass to be readablethrough the sight, bearings associated with the ring at fixed pointsimmediately adjacent to the compass reflecting prism, a secondreflecting prism rotatably mounted in said bearings above and in closeproximity to the first mentioned prism to be adjusted to externallycatch and reflect an image, and a center line indication to which theimage and the reflected compass reading are centered in a single fieldof vision through the sight.

4. An apparatus for taking bearings comprising, a compass, a ringassociated with said com pass to encircle the face thereof and revolublein a horizontal plane, a sight at one side of said ring, a fixedreflecting prism carried bythe ring at a point opposite the sight toreflect compass I readings to show variations in the line of sight asthe ring is revolved, a second reflecting prism carried by said ringimmediately adjacent to and above the first mentioned prism andoscillatable upon a horizontal axis to permit adjustment of the secondprism to focus desired terrestrial and celestial images to bring thesame into the fleld of vision with a compass reflecting prism. and meansto indicate leveling of the ring transversely to the line of sight.

5. An apparatus for taking bearings comprising, a compass, a ringassociated with said compass to encircle the face thereof and revolublein a horizontal, plane, a sight at one side of said ring, a fixedreflecting prism carried by the ring at a point opposite the sight toreflect compass readings to show variations in the line of sight as thering is revolved, a second reflecting prism carried by said ringimmediately adjacent to and above the first mentioned prism andoscillatable upon a horizontal axis to permit adjustment of the secondprism to focus desired terrestrial and celestial images to bring thesame into the field of vision with a compass reflecting prism, meansto-indicate leveling of the ring transversely to the line of sight, andmeans to indicate on the first prism a hairline center to permitaccurate determination of compass readings and to establish a center towhich the reflected image can be centered to be exactly in the line ofsight by rotation of the ring.

6. An apparatus for taking bearings comprising, a compass, a ringrevolubly associated with rotatable on a vertical axis, a sight carriedby said ring at one side, a bearing and supporting structure carried bysaid ring at a point substantially diametrically opposite the .sight, a'reflecting prism held in fixed mounting by said supporting structure tobe in a line from the sight diametrically across the compass, said prismbeing disposed to reflect compass readings through the sight and havinga center line indicated directly from the sight across the compasscenter, a second reflecting prism, bearings mounting said secondreflecting prism in thebearing and supporting structure to beoscillatable on a horizontal axis above the first reflecting prism andwith one of its angular corners closely adjacent to a corner of thefirst prism, and means by which said second reflecting prism can beoscillated to fOC-lS desired terrestrial and celestial images.

7. An apparatus for taking bearings comprising, a compass, a ringrevolubly associated with said compass to encircle the face thereof andbe rotatable on a vertical axis, a sight carried by said ring at oneside, a bearing and supporting a structure carried by said ring at apoint substantially diametrically opposite the sight, at reflectingprism held in fixed mounting by said supporting structure to be in aline from the sight diametrically across the compass, said prism beingdisposed to reflect compass readings through the sight and having acenter line indicated directly from the sight across the compass center,a sec- 0nd reflecting prism, bearings mounting said secondreflectingprism in the bearing and supporting structure to be oscillatable on ahorizontal axis above the first reflecting prism and with zontal plane,a sight carried by said ring for viewing radially with respect to thecompass, a

I a showing of an external image.

9. With a compass, a ring revolubly associated with the compass, abracket carried by the ring, a sight lined up to direct a line of sightsubstantially radially with respect to the ring, a reflecting prismcarried by said bracket overhanging inside of the ring to catch areading of the compass card in line with the line of sight, a secondprism swingably mounted closely adjacent to the first prism to beoscillated on a substantially horizontal axis to draw in and reflect animage of an external body to be closely adjacent and within the sightline, and means also visible in the line of sight to indicate levelingof the ring.

10. In combination with a compass, a support revolubly mounted to beturned with respect to the compass upon a vertical axis substantiallycoinciding with the axis of the compass card, a reflecting prism carriedby said supporting structure in fixed mounting to reflect and show acompass reading to be viewed in a line across the compass card, and asecond reflecting prism adjustably mounted closelyadjacent to the upperpart of the first prism and swingable upon an axis substantially atright angles to the axis upon which the supporting structure is moved tothus permit focusing to catchand reflect an external aoaaoes image inthe same field of vision with the reflected showing of the portion ofthe compass card in said first prism.

11. In combination with a compass structure, a ring revolubly associatedwith the compass to be adjustable on a vertical axis substantiallycoinciding with the axis of the compass, a sight carried on the nearside of the ring, a reflecting prism fixedon the far side of the ringto'be viewed through said sight and to reflect an effective compassreading, and a second reflecting prism carried by said ring closelyadjacent to the upper part of the first prism and adjustably mounted tobe swung upon an axis substantially at right angles to the axis ofadjustment of the ring to thus permit focusing to show an image of anexternal reflection in juxtaposition to and in the field of vision withthe reflected compass reading as seen through the sight.

12. In combination with a' compass, a ring mounted upon the compass andrevoluble on a vertical axis substantially coinciding with the axis ofthe compass, a prism carried by said ring at one side to reflect aneffective reading of the compass to be viewed substantiallydiametrically across the ring and having one of its angles disposedupwardly and extending substantially at right angles to the axis ofrotation of the ring, and a second prism swingably mounted upon the ringadjacent to the upper angle of the first prism for adjustable swingingmovement on an axis substantially at right angles to the axis ofrotation of the ring to thus be adjustable to show an image of anexternal reflection closely adjacent to and in the field of vision withthe reflected reading of the compass card as shown in the first prism.

BURTON M. GREEN.

